The invention relates to a process for fault detection on defined structures on surfaces of electrical components or the auxiliary means required to manufacture these components, wherein the actual structure provided in each respective case is scanned with a test beam.
In the manufacture of semiconductor components, for example, both the required sets of masks and the single semiconductor discs and semiconductor components must be checked optically for faults in the desired structures during the manufacturing processes. Since in the course of technological development, the component structures become smaller and smaller and the integrated circuits grow more and more complex, also the necessary structure testing becomes increasingly difficult and technically more elaborate. In view of the great complexity and the resulting high development and manufacturing costs of integrated circuits, the detection of structure faults or structure deviations at as early a stage of the development and manufacture as possible is gaining more and more significance. Optical testing of the highly integrated circuits and the masks required for their manufacture under a microscope is no longer purposeful.
Several processes have meanwhile been suggested for testing and controlling structures on semiconductor discs or masks by machine. In one process, an actual structure is compared with a second actual structure by means of fragmented, optical ray paths. The two pictures may also be made to register in the form of a video picture, with the composition picture then being evaluated.
In another known process, the structure to be tested is scanned with the aid of a test beam and decomposed into picture points. The thus digitalized total picture is put into a data processor in which the scanned structure is compared to desired pictures, desired structures or structure regulations contained in a store. Such a process is, for example, described in German patent application No. P 27 00 252.4.
In the first above-decribed process, structure faults are detected from a non-registration of the two composite pictures, whereas in the second above-mentioned process, fault detection is only possible after a comprehensive data processing operation. Both known processes require enormous optical and electronic expenditure.